A form of process for the production of a foam-backed cushion portion comprising a foam core with a cover thereon involves introducing a cover portion to form the cover of the cushion portion into the first mold portion of a mold for producing the cushion portion. The cover is fixed by a second mold portion of the mold, along peripherally extending contact portions between the two mold portions, and thus the mold is closed to provide a mold cavity with the cover portion bearing against a part of the internal surface thereof. A reaction mixture is then introduced into the mold cavity and foams up during reaction thereof, thereby filling the foam cavity and at the same time becoming joined to the cover portion in the mold cavity.
Hitherto such a procedure can be effected by means of an apparatus in which the peripherally extending contact portions of the first and second mold portions have generally sharp edges in order to ensure that the mold portions are securely sealed with respect to each other, or the apparatus used does not have selaling edges of that kind along the peripherally extending contact portions, with the result that the mold cavity is then no longer soundly sealed. However the first form of the apparatus which has the sealing edges to seal off the mold cavity suffers from the disadvantage that the sealing edges become impressed into the cover portion which is for example a portion of textile material coated with a lining on the inward side thereof which is towards the foam core of the cushion portion, and that impression can be at least seen by the eye in the cover of the cushion portion, which has a generally detrimental effect on the visual appearance of the cushion portion. In extreme cases, it is even possible for the sealing edges of the mold portions to actually cut into the cover portion in the mold cavity. It is in order to prevent the sealing edges of the mold portions from pressing into or even cutting into the cover portion that recourse may be made to the second form of the apparatus which does not have sealing edges of that kind. In that case however, as already indicated, it is no longer possible to ensure that the mold cavity is properly sealed off along the peripherally extending contact portions where the first and second mold portions meet. As a result, although the appearance of the cover is improved by virtue of eliminating the pressure marks formed by the sealing edges of the first form of apparatus discussed above, the reaction mixture which foams up in the mold cavity can penetrate between the mold portions and in an extreme case through the cover portion, and that can result in undesirable hardening of the cover portion and therewith equally undesirable hardening of the cushion portion itself.